I'm a Red Hat admin and am running RHEL5.1 on a number of machines.
RHEL5 is a dependable and stable operating system, as are by far most of
the utilities it comprises. One RHEL5 offering to be avoided at all
costs is openldap-*-2.3.27. Apart from anything else it is built with
bdb 4.3.29 support. db4.3 has been condemned as unsuitable by the
OpenLDAP developers. There are other reason too, but this is the most
important.

I (and other Red Hat admins in the know) run Buchan Milne's alternative
which comprise discrete, patched db-4.2.52 and can exist beside the
RHEL5 offering. This is an utterly stable and dependable product; it is
available at http://staff.telkomsa.net/packages/rhel5Server/openldap/.